There's an interesting article on decks in the June 2006 issue of Home magazine with a list of materials, their performance and maintenance. I didn't know they made decks from aluminum; they're powder-coated and need the least maintenance. Natural wood (not pressure-treated) requires the most maintenance, though it's similar to pressure-treated, and has a warranty of 10+ years. Lots more useful information. There's a Trex ad in the magazine, btw; it looks like they have more choices now.
From a Country Home e-mail:
Introducing the Trex® Create Your Space® Deck Designer - an interactive tool to help you create your space. With a few clicks of your mouse, customize your Trex deck with different colors, textures, design shapes, and outdoor living accessories to create the outdoor living space of your dreams. For help in designing the deck of your dreams, call 1-800-BUY TREX, ext. 1337, or start now at mytrexdeck.com.